Charles Petzold

Sometime last year I bought Not by Genes Alone: How Culture Transformed Human Evolution by Peter J. Richerson and Robert Boyd (University of Chicago Press, 2005), and it's been sitting on my shelf pleading for attention ever since. I'm glad to finally get to it. The authors are (respectively) professors of environmental science and anthropology at the University of California. This book apparently covers much the same ground as their earlier book Culture and the Evolutionary Process (University of Chicago Press, 1985) but is targetted to a wider, less academic, audience.

The authors ask, What makes humans different from every other species on the earth? One unique trait is that humans can be found almost everywhere there is land. You don't expect to find chimpanzees in the Arctic, or polar bears in Africa, but you'll find humans in both places.

Is this ability to survive in varied climates and environments a biological trait that has evolved through natural selection? Hardly! Although minor adaptations (such as skin color) certainly occur in different environments, humans around the world are basically the same. Moreover, drop a group of Americans — even a group of really smart Microsoft employees — in an uninhabited region of Africa or the Arctic, and they will surely die. They wouldn't know how to get food and how to protect themselves from the weather. What little survival they manage would probably be based on something somebody once saw on the Discovery channel.

Humans survive in lots of different environments because of culture, the entire collection of things we learn from parents, teachers, and peers through observation and imitation. Culture teaches us how to eat and otherwise survive in inhospitable environments. This much is fairly obvious. But the implications are quite fascinating, as Richerson and Boyd discuss their decades of research in a tightly-argued 257 pages (not counting the copious footnotes and extensive bibliography) and seven chapters:

1. Culture is Essential
2. Culture Exists
3. Culture Evolves
4. Culture is an Adaptation
5. Culture is Maladaptive
6. Culture and Genes Coevolve
7. Nothing About Culture Makes Sense Except in the Light of Evolution

In understanding culture, it helps to look at it from a Darwinian perspective, that is, in terms of populations, adaptations, and evolution. (And here I should note that the authors are talking about much broaders concepts than Richard Dawkins' memes, which are rather granular nuggets of information.) Culture is an evolutionary survival mechanism that can adapt faster than biological evolution, and culture has its own forms of selection. Those who do not play well with others are often denied mates, or incarcerated, or (in the most brutal of cultures) actually executed.

Where this really gets interesting is in the coevolution of genetics and culture. For example, other primates can certainly learn some simple tasks through imitation, but no other species comes close to the human ability to imitate. The genetic imitation trait was therefore necessary for culture to exist at all, and culture then was able to introduce additional survival mechanisms that helped the preservation of the human species.

Culture requires a mix of conformity and ingenuity. Culture is easier to preserve if it's adopted without question, but culture also needs to adapt to changes in living conditions. An adaptable culture requires people with enough of a rebellious streak of individuality to try something different, for example a slightly different way of making the kayak. (The authors are big on kayaks; they're even pictured on the book's cover.)

Think about being plucked down on an Arctic beach with a pile of driftwood and seal skins and trying to make a kayak. You already know a lot — what a kayak looks like, roughly how big it is, and something about its construction. Nonetheless, you would almost certainly fail (We're not trying to dis you; we've read a lot about kayak construction, and we'd at best make a poor specimen, without doubt). Even if you could make a passable kayak, you'd still have a dozen or so similar tools to master before you could make a contribution to the Inuit economy. (p. 130-1)

The authors argue that language could be a product of a coevolution. Very primitive language could aid cultural cooperation and learning, and then culture itself could select for better language ability. One of the more interesting areas of study involves the high-level of cooperation required in today's societies. In terms of genetic evolution, cooperation only makes sense between closely related relatives, or in a reciprocation relationship, or with small groups. Yet, we seem to have developed large complex societies with a division of labor and a surprising degree of trust. These "tribal social instincts" (as the authors call them) seem to have emerged during the Pleistocene epoch.

These new tribal social instincts were superimposed onto human psychology without eliminating those that favor friends and kin. Thus, there is an inherent conflict built into human social life. The tribal instincts that support identification and cooperation in large groups are often at odds with selfishness, nepotism, and face-to-face reciprocity. Some people cheat on their taxes, and not everyone pays back the money he borrows. Not everyone who listens to public radio pays her dues. People feel deep loyalty to their kin and friends, but they are also moved by larger loyalties to clan, tribe, class, caste, and nation. Inevitably, conflicts arise. Families are town apart by civil war. Parents send their children to war (or not) with painfully mixed emotions. Highly cooperative criminal cabals arise to prey upon the production of public goods by larger scale institutions. Elites take advantage of key locations in the fabric of society to extract disproportionate private rewards for their work. The list is endless. The point is that humans suffer these pangs of conflict; most other animals are spared such distress, because they are motivated only by selfishness and nepotism. (p. 215)

They further argue that the emotion of empathy (found nowhere else in the animal kingdon) seems to have evolved in humans as a necessary prerequisite for behaving in ways that preserve larger groups, which pure genetic evolution can't handle. These are two researchers who discern legitimate altruism in the ways that humans interact.

Richerson and Boyd have written not only a thought-provoking book, but one that is often witty as well. For example, at one point they discuss a custom among the people of the island of Ponpae that has evolved to the point where prestige is based on the production of the largest yam, some of which require 12 men to carry. They note, "In California, where we live, the twelve-man yam comes to mind when we see a Hummer II rolling down a Los Angeles boulevard." (164)